1. Field of the Invention
The present invention relates to a blood pressure meter and a mobile terminal having the blood pressure meter and, more particularly, to a blood pressure meter made more portable by simplifying the structure of a cuff for compressing or decompressing a body part of a testee, and a mobile terminal having the blood pressure meter.
2. Description of the Related Art
Blood pressure is classified into arterial pressure, capillary pressure, and venous pressure, but the term is usually used to refer to arterial pressure. Arterial pressure varies during each heartbeat. The blood pressure when a ventricle of the heart contracts and pushes blood out to an artery is referred to as systolic pressure. The systolic pressure is the maximum blood pressure in the blood vessels. When the ventricle of the heart expands and does not push blood out, the artery walls are elastic and maintain some blood pressure. This pressure is referred to as diastolic pressure. The diastolic pressure is the minimum blood pressure. The difference between the systolic pressure and the diastolic pressure is referred to as the pulse pressure.
Blood pressure varies depending on the conditions. Accordingly, it is difficult to clearly determine blood pressure with one measurement. The blood pressure measured on an empty stomach right after waking is referred to as basic pressure. The basic pressure is helpful for medical diagnosis. In real life, it is necessary to measure the blood pressure several times under various conditions. Therefore, there is a need for a portable electronic blood pressure meter which can be handled at home by general users.
An apparatus which can keep a constant contact area between a finger and a cuff regardless of the thickness of the finger is disclosed in U.S. Pat. No. 5,511,551, entitled “Cuff for blood pressure meter.” A foldable cuff is disclosed in U.S. Pat. No. 5,807,266, entitled “Finger-type Blood Pressure Meter with a Flexible Foldable Finger Cuff.” An apparatus which can bring a cuff into close contact with a finger by manually pulling the cuff is disclosed in U.S. Pat. No. 5,119,823, entitled “Cuff Wrapping Apparatus for Blood Pressure Meter.”
The above-mentioned patent inventions have a common feature that a cuff is fitted onto a finger and compressed or decompressed with air pressure. However, since a volume of air must be injected into the cuff in order to finely adjust the pressure of the cuff, the size of the cuff is increased. Miniature air-pressure cuffs are possible but are not capable of precise decompression for measuring blood pressure. In addition, mechanical parts such as a pump, a drive source, and a valve, for adjusting the pressure of the cuff, hinder the decrease in size of the blood pressure meter. On the other hand, in order to check blood pressure for health care at all times, the portability of the blood pressure meter should be improved. Therefore, there is a need for a small, lightweight blood pressure meter having a simple cuff which can replace the air-pressure cuff.